Juan Martin Del Potro of Argentina reacts after missing a shot during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski)

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Juan Martin Del Potro of Argentina reacts after missing a shot during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski)

Juan Martin Del Potro of Argentina reacts after missing a shot during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski) (/ AP)

Juan Martin Del Potro of Argentina receives treatment after falling during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski)

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Juan Martin Del Potro of Argentina receives treatment after falling during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski)

Juan Martin Del Potro of Argentina receives treatment after falling during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski) (/ AP)

Juan Martin Del Potro of Argentina grimaces as he rolls on the ground after falling during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski)

/ AP

Juan Martin Del Potro of Argentina grimaces as he rolls on the ground after falling during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski)

Juan Martin Del Potro of Argentina grimaces as he rolls on the ground after falling during his Men's singles quarterfinal match against David Ferrer of Spain at the All England Lawn Tennis Championships in Wimbledon, London, Wednesday, July 3, 2013. (AP Photo/Dominic Lipinski) (/ AP)

Murray will play No. 24 Jerzy Janowicz, a 7-5, 6-4, 6-4 winner over Lukasz Kubot in the first Grand Slam meeting between two Polish men.

Going against the 54th-ranked Verdasco, Murray certainly made things interesting for the British fans, looking for one of their own to call a Wimbledon champion for the first time in 77 years. He dropped the first two sets, unable to handle Verdasco's pinpoint serves that reached as high as 136 mph.

Slowly, though, he crept back into the match. In the sixth game of the fourth set, Murray saved a pair of break points - first with a service winner, then with one of his 13 aces. Three games later, he broke Verdasco, then served out the set. In the fifth set, the players held serve for 10 straight games. In the 11th, Murray broke, then served out the match at love.

"I played at a very high level," said Verdasco, appearing in a Grand Slam quarterfinal for the first time since the 2010 U.S. Open. "And to not be able to win is painful, of course."

It was Murray's second comeback from two sets down at Wimbledon, adding to a 2008 victory over Richard Gasquet.

"Yeah, you're obviously concerned," Murray said. "You're more concerned about losing the match, not thinking so much that, I'm going to lose at Wimbledon. You're concerned how the match is going and that you may lose. But when you've been in that position a lot of times, you know how to think through it and not get too far ahead of yourself."

In the earlier match, it looked as if del Potro would be done before he even broke a sweat.

His left knee mummified in athletic tape, the 6-foot-6 Argentine chased an overhead into the corner, but his left foot slipped out from under him. His already aching knee straightened suddenly, then bent backward. Del Potro crumpled to the ground and rolled twice - into the far edge of the court.

After a break of about 10 minutes, del Potro was back on the court. He broke Ferrer twice in the first set, then moved easily through the second and third against one of the grittiest players in tennis.

"I have my knee problem, but always the opponent, the other players, can have different injuries, too," del Potro said. "You have to be strong, more than the rest."

Across the way, on Court 1, Janowicz beat Kubot to become the first Polish man to reach a Grand Slam semifinal.

After the match, the players hugged at the net for more than 15 seconds, then exchanged shirts the way soccer players often do at their games. A bit later, Janowicz sat in his chair, clasped his hands over his nose and cried.

"Right now, I'm the most happy person in the world," Janowicz said.

About playing Murray, who won his first Grand Slam tournament last year at the U.S. Open, Janowicz said: "I hope Andy will feel some kind of pressure. I'm sure he'll feel some kind of pressure because Great Britain is waiting for the English champion in Wimbledon."

During a tournament with more than its share of twists and turns - to say nothing of slips and slides - Djokovic and del Potro have gone through virtually unscathed, on the scoreboard at least. Neither man has dropped a set.

Djokovic overcame a two-break, 3-0 deficit in the second set to cruise to his latest victory over Berdych, the 2010 Wimbledon runner-up. Djokovic is in his 13th straight Grand Slam semifinal and in search of his seventh major title.

"Coming into the semifinals, I feel physically fresh," Djokovic said.

No. 8 del Potro wouldn't quite use those terms to describe himself.

He is, however, starting to show the form he used to win his only major championship, the U.S. Open in 2009, which also marks the last time he reached a Grand Slam semifinal. He is 3-8 lifetime against Djokovic, though one of those victories came here, at the All England Club, when he beat the Serb in the Olympic bronze-medal match last year. Del Potro also won their last meeting, earlier this year on hard court at Indian Wells.

"He struggled with injuries in last few years, but every time he comes back, he comes back very strong because he just has this talent," Djokovic said.

Indeed, del Potro - nicknamed "The Tower of Tandil" after his hometown in Argentina - has won despite being wracked with pain since Saturday, when he slipped and hyperextended his left knee for the first time.

He's not the only one to slip at Wimbledon during this fortnight, and he wasn't the only one hurting Wednesday.

Ferrer has also been dealing with ankle and toe issues. He cut short his pre-match hitting session because of pain in his ankle but said that was no excuse. Ferrer, who crossed the net to run toward del Potro to check on him when he fell, said he didn't see much change in his opponent's play after the injury.

"Juan Martin, he was more focused, he was playing more aggressive than me and he served very, very good in all three sets," Ferrer said.